Results and discussion

Data recorded in Figure 1
indicated that total coliforms were not detected in any sample taken
from bottled water. In the desalinated water, surface water, and well
water, total coliforms were detected with percentages of 12.9, 80, and
100.0, respectively. However, log counts of total coliform bacteria
(MPN/100 ml) in desalinated, surface, and well water were 0.0–1.60,
0.0-≥ 4.38, and 1.60-≥4.38, respectively. The log mean values were 3.79
± 3.40 and 3.86 ± 3.22 (MPN/100 ml) in samples taken from surface and
well water, respectively. In previous studies, total coliform bacteria
were detected in different water sources with various mean values and
percentages [28,31,23,33,34].
There was no significant correlation in the level of total coliforms
between well and surface water. As previously cited, total coliform
counts must not be detected in any 100 ml water samples [35,17,24,11].
Therefore, results of total coliforms recorded in the present study
showed that all examined samples from wells (100.00%) and most surface
water (80.00%) exceeded the guideline values recommended in accordance
with international standards [3,17,24].

The
most common group of indicator organisms used in water quality
monitoring are coliforms. These organisms are representative of
bacteria normally present in the intestinal tract of mammals including
human, so they provide a general, albeit adequate, index of faecal
contamination of drinking water [36,24,26,38]. Moreover, the presence of coliforms in drinking water could also indicate a breakdown of the treatment process [28].
The transportation of desalinated water by tanker does not contribute
significantly. Such contamination obviously occurs during storage in
the house reservoir (earth) and is possibly implicated, at least
partly, in the increased prevalence of diarrhoea [23].

From the results recorded in Figure 2,
it is evident that faecal coliforms were not detected in any samples
taken from bottled water, while from desalinated water, only one out of
31 (3.23%) samples was found positive for faecal coliforms. However, 9
out of 15 (60.0%) and 29 out of 33 (87.88%) specimens were found
positive for faecal coliforms in samples taken from surface and well
water, respectively. The log counts of faecal coliforms (MPN/100 ml)
ranged from 0.0 to 1.6; 0.0 to ≥ 4.38 and 0.0 to ≥ 4.38 in desalinated,
surface, and well water, respectively. Logarithmic mean values (MPN/100
ml) were 3.47 ± 3.23 and 3.40 ± 3.08 in surface and well water,
respectively. There was no significant correlation in the level of
faecal coliforms between well and surface water. These results
indicated that most samples taken from wells (87.88%) and surface water
(60.00%) had higher faecal coliforms with respect to the international
guideline value, in which drinking water must be free from faecal
coliforms [22,17,24,11,26,9]. Different coliform counts were previously recorded in groundwater samples [28,31,23,39,40].

Indicators
such as faecal coliforms are not the best, because their effectiveness
will be minimised in geographical zones when the temperature is high [41,26,42]. However, well water is at risk of contamination, as indicated by the presence of faecal coliforms [43,24,5,7,11,44,20].

It is evident from Figure 3
that faecal streptococci were not detected in any samples taken from
bottled water. Two out of 31 (6.45%) desalinated water samples, 8 out
of 15 (53.33%) surface water samples, and 19 out of 33 (57.58%) well
water samples were found positive for faecal streptococci. Logarithmic
range values of faecal streptococci (MPN/100 ml), however, were
0.0–1.6, 0.0–2.18, and 0.00–3.38 in samples taken from desalinated,
surface, and well water, respectively. The log mean values of faecal
streptococci (MPN/100 ml) were 1.65 ± 1.07 and 2.28 ± 1.97 in surface
and desalinated water. There was a significant correlation at p = 0.05
in the level of faecal streptococci between surface and well water.
With regard to international guideline values, in which water must be
free from faecal streptococci, 6.45% of the desalinated water, 53.33%
of the surface water, and 57.58% of the well water was considered to be
unfit for drinking purposes. Faecal streptococci were previously
isolated with various frequencies [28,31,33].
Enterococcus species were formerly classified in the genus
streptococci. They are primarily commensurate with residence in the
intestine, though some also cause gastroenteritis, nosocomial
infection, endocarditis, intra-abdominal infection, surgical wound
infection, and urinary tract infections [45,46,19,17,24,11].

As
regards the bacteriological examination of water sources carried out in
this study, high total coliforms, faecal coliforms, and faecal
streptococci in surface and most well water are considered an
indication of recent faecal pollution from human or animal excreta,
which may reflect the possibility of potential health hazards [42].
The primary risk of consuming untreated water is the transmission of
communicable diseases by pathogenic organisms. Those present in aquatic
environments can be of natural origin or may be discharged by humans
and other warm-blooded animals. However, the water, which is not
suitable for drinking, may be usable for irrigation or for other
domestic purposes. Thus, it can be seen that each use of water imposes
its own limits on the degree of pollution that can be considered
acceptable [1,17,24].
Drinking only from desalinated water sources was associated with
diarrhoea as compared with drinking only from bottled water or from any
other sources [23].
Water from the valleys and wells of the study area was grossly polluted
and was used regularly for purposes other than drinking [23,5-7].

The coliform group comprises strains of the four genera of the
intestinal group: Escherichia, Enterobacter, Klebsiella, and
Citrobacter. The number of Escherichia and Enterobacter remains much
higher in the intestine than do the remaining two [1,26,9].

The frequency distribution of the different microorganisms isolated from the examined samples is given in Table 1.
A total of 114 isolated bacteria included 10 from desalinated water, 45
from surface water, and 59 from wells. These were typed to be 23
Escherichia coli (E. coli), 13 Klebsiella pneumonia, 7 Klebsiella
oxytoca, 20 Enterobacter cloacae, 6 Eenterobacter aerogens, 7
Eenterobacter agglomerans, 3 Enterobacter gergoviae, 10 Citrobacter
freundii, 8 Citrobacter diversus, 12 Proteus vulgaris, and 5 Proteus
mirabilis, with percentages of 20.18, 11.40, 6.14, 17.54, 5.26, 6.14,
2.63, 8.77, 7.02, 10.52, and 4.39, respectively. Most of these
bacterial species had been previously isolated from different water
sources, although their percentages varied [47,27,31,40,11].

It is clear that out of all possibilities, E. coli can best fulfil
conditions possible to act as an ideal indicator of faecal pollution.
These organisms survive longer in water than most pathogens, and thus
can detect recent as well as earlier pollution. In terms of public
health significance, E. coli has frequently been reported to be the
causative agent of traveller's diarrhoea, urinary tract infection,
haemorrhagic colitis, and haemolytic uraemia syndrome. Moreover,
Klebsiella pneumonia is associated with pneumonia and upper respiratory
tract infection. However, Enterobacter and Citrobacter species have
also been previously reported as causes of cystitis, enteritis,
pneumonia, diarrhoea, and food poisoning [48,17,24,11].
Proteus species are apparently of epidemiological importance in summer
diarrhoea in infants and in food-borne outbreaks. Proteus vulgaris in
association with other bacteria has been reported to be the causative
agent of cystitis and pyelitis [48,25,17,24,11].

Based on the above assessments, although bottled water may be of
good quality in the Khamis Mushait Governorate urban area, the public
supply of both desalinated water distributed via an urban water network
system to areas of city quarters and conventional water sources such as
wells and surface water cannot be ignored by local water authorities.
They should consider a proper regular monitoring programme (i.e. wells
and surface water microbial source tracking system) to determine the
primary sources of contamination, their contribution, health threat,
and geographic distribution. In addition, they ought to make
recommendations and to develop appropriate control measures to avoid
any sudden public health risk from such a vital water source [23,11].